1. Field of the Invention
The present invention relates to a display device or a television receiver used in combination with a computer device such as a personal computer. More particularly, it relates to a display device for giving remarkable reduction in disturbing noise which adversely affects a magnetic memory device, for instance, a floppy disc drive.
2. Description of Prior Art
Personal computers have more and more been developed and used in wide range. Various type of the personal computers have been presented in commercial scale along with a display device or color-television receiver.
It is a recent tendency to provide a separate type personal computer in which a main body of C.P.U., a key board and a display device are separated and a magnetic memory device such as a floppy disc drive (hereinbelow referred to as a FDD) is placed in the C.P.U.
FIG. 1 is a schematic view in combination of these devices. In FIG. 1, a reference numeral 1 designates a main casing inclusive of a C.P.U. as an essential part of a personal computer (referred to as C.P.U.), numeral 2 designates a magnetic memory device consisting of FDD as an auxiliary memory device, a numeral 3 designates a key board and a numeral 4 designates a display device which may be one of an exclusive use or a television receiver which receives a signal at an antenna input part through a converter. In the C.P.U. 1 in such a system, a magnetic head (not shown) is provided in the magnetic memory device 2 and is electromagnetically coupled to a disket used for the magnetic memory device to write in and read out signals. In the system, however, when a needless magnetic field is formed around the magnetic head, there causes overlapping of needless noise coupled with the magnetic head on the original signal thereby causing malfunction of the magnetic memory device 2. Particularly, when the display device 4 is directly put on the C.P.U. 1 as shown FIG. 1, electromagnetic field noise emitted from the display device 4 is directly effected to the magnetic memory device 2 to cause a fatal defect. As electromagnetic field noise emitted from the display device 4, there is leakage flux having a horizontal deflection frequency produced from coils which are mainly used in a horizontal deflection system comprising a deflection yoke, a flyback transformer, a horizontal width adjusting coil and so on and switching noise in a power source circuit. The former is noise of 15.7 KHz-24 KHz and the latter is one having a frequency component produced by switching the power source circuit. Interference noise is also generated from a copper-layered pattern on a substrate on which a power source and a deflection circuit are provided. Thus produced electromagnetic field noises are mainly caused by a leakage magnetic field emitted from the horizontal deflection coil in the deflection yoke. Accordingly, when an arrangement as shown in FIG. 1 is taken, the magnetic memory device 2 should not be adversely affected by the leakage magnetic field produced from the horizontal deflection coil to avoid malfunction of the device 2.
As an attempt to prevent the malfunction of the magnetic memory device 2 caused by the leakage magnetic filed from the horizontal deflection coil, it is considered that a shielding mat is interposed between the C.P.U. 1 and the display device 4. It is, however, disadvantageous in that handling works are troublesome and the quality of the system as a commodity is poor.